Micro LED display device and method of fabricating the same

ABSTRACT

Disclosed is a micro light emitting diode (LED) display device which is capable of implementing a full color of high resolution, the micro LED display device including: a micro LED driving substrate (backplane) in which a plurality of CMOS cells is arranged in rows and columns; and a micro LED panel which is flip-chip bonded onto the micro LED driving substrate, and includes a plurality of micro LED pixels electrically connected with the plurality of CMOS cells, in which the micro LED panel includes the plurality of micro LED pixels formed by etching a first surface of an emission structure along a unit pixel region, and a plurality of separators formed on a second surface of the emission structure corresponding to positions of portions formed by etching the emission structure in a vertical direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/888,943, filed on Feb. 5, 2018, which claims the priority to and thebenefit of Korean Patent Application No. 10-2017-0051892, filed in theKorean Intellectual Property Office on Apr. 21, 2017, the entirecontents of which are incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure

The present invention relates to a micro light emitting diode (LED)display device and a method of fabricating the same, and moreparticularly, to a micro LED display device which has a separatorstructure between micro LED pixels, and a method of fabricating thesame.

2. Background of the Disclosure

A light emitting diode (LED) is a sort of semiconductor device whichconverts electric energy to light energy. The LED has advantages in lowpower consumption, semi-permanent life, high response speed, safety, andeco friendliness, compared to an existing light source, such asfluorescent light and incandescent light.

In this respect, a lot of research on replacement of the existing lightsource with the LED has been conducted, and there increases the case inwhich the LED is used as a light source of a lighting device, such asvarious lamps used in indoor and outdoor places, a liquid crystaldisplay device, an electronic display, and a streetlamp.

Recently, an LED industry makes a new attempt to be applied to variousindustries beyond an existing traditional lighting range, andparticularly, research is actively conducted in a low power drivenflexible display field, an attachment-type information display devicefield for monitoring a human body, a vital reaction and deoxyribonucleicacid (DNA) sensing field, a bio convergence field for verifyingeffectiveness of optogenetics, and a photonics textile field in which aconductive fiber is combined with an LED light source.

In general, when an LED chip is fabricated in a size of several toseveral tens of micros which is small, it is possible to overcome adisadvantage in that the LED chip is broken when an inorganic materialis bent according to a characteristic of the inorganic material, and itis possible to broadly apply the LED chip to various application fieldsup to a wearable device and a medical device for body insertion, as wellas the foregoing flexible display, by giving flexibility by transferringthe LED chip to a flexible substrate. However, when the LED light sourceis applied to the foregoing application fields, it is necessary todevelop a light source which is thin and flexible, and has a size in amicro level, and in order to give flexibility to the LED, there is ademand for a process of transferring a separated thin film GaN layer toa flexible substrate in an individual or desired arrangement.

According to the research and development on the micro LED technologyfield, there currently exists a micro LED panel fabricating technologywhich is capable of implementing one color (that is, red, green, andblue), but a micro LED panel fabricating technology which is capable ofimplementing a full color has not been reported in the academic world orthe industrial world as yet. Accordingly, it is necessary to develop amicro LED panel which is capable of implementing a full color.

SUMMARY OF THE DISCLOSURE

An object of the present invention is to solve the foregoing problemsand other problems. Another object of the present invention is toprovide a micro light emitting diode (LED) display device having astructure in which a plurality of separators is repeatedly formed on agrowth substrate corresponding to locations between micro LED pixels,and a method of fabricating the same.

Another object of the present invention is to provide a micro lightemitting diode (LED) display device having a structure in which aplurality of separators is repeatedly formed on a first conductivesemiconductor layer corresponding to locations between micro LED pixels,and a method of fabricating the same.

Another object of the present invention is to provide a micro lightemitting diode (LED) display device which is capable of implementing afull color by injecting an R/G/B color light changing material betweenseparators, and a method of fabricating the same.

Another object of the present invention is to provide a micro lightemitting diode (LED) display device which is capable of implementing afull color by injecting a fluorescent substance for emitting a whitecolor between separators and disposing a color filter on the fluorescentsubstance, and a method of fabricating the same.

An exemplary embodiment of the present invention provides a micro lightemitting diode (LED) display device, including: a micro LED drivingsubstrate (backplane) in which a plurality of CMOS cells is arranged inrows and columns; and a micro LED panel which is flip-chip bonded ontothe micro LED driving substrate, and includes a plurality of micro LEDpixels electrically connected with the plurality of CMOS cells, in whichthe micro LED panel includes the plurality of micro LED pixels formed byetching a first surface of an emission structure along a unit pixelregion, and a plurality of separators formed on a second surface of theemission structure corresponding to positions of (dent) portions formedby etching the emission structure in a vertical direction.

Another exemplary embodiment of the present invention provides a methodof fabricating a micro light emitting diode (LED) display device, themethod including: fabricating a micro LED driving substrate (backplane)in which a plurality of CMOS cells is arranged in rows and columns;fabricating a micro LED panel including a plurality of micro LED pixelsformed by etching a first surface of an emission structure along a unitpixel region, and corresponding to the plurality of CMOS cells;disposing a plurality of bumps on the micro LED driving substrate, andflip-chip bonding the micro LED panel on the micro LED driving substrateon which the plurality of bumps is disposed; coating a second surface ofthe emission structure with a photo resist, disposing mask patterns onthe photo resist, and performing an exposure process of emitting light;and forming a plurality of separators on the second surface of theemission structure by performing a developing process on the photoresist which passes through the exposure process.

The effects of the micro LED display device and the method offabricating the same according to the exemplary embodiments of thepresent invention will be described below.

According to at least one of the exemplary embodiments of the presentinvention, the plurality of separators is periodically disposed on thegrowth substrate corresponding to the locations between the pixels,thereby effectively removing color interference between the pixels andeasily applying the R/G/B color light changing materials onto the growthsubstrate.

According to at least one of the exemplary embodiments of the presentinvention, the plurality of separators is periodically disposed on theemission structure corresponding to the locations between the pixels,thereby effectively removing color interference between the pixels,minimizing light scattering due to the growth substrate, and easilyapplying the R/G/B color light changing materials onto the emissionstructure.

According to at least one of the exemplary embodiments of the presentinvention, the plurality of separators is periodically disposed on theemission structure corresponding to locations between the pixels,thereby effectively removing color interference between the pixels,minimizing light scattering due to the growth substrate, and easilyapplying the white light emitting fluorescent substance onto theemission structure.

However, the effects achieved by the micro LED display device and themethod of fabricating the same according to the exemplary embodiments ofthe present invention are not limited to the foregoing matters, andnon-mentioned other effects may be clearly appreciated to those skilledin the art on the basis of the descriptions below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a micro LED display deviceaccording to a first exemplary embodiment of the present invention.

FIG. 2 is a diagram referred for illustrating the number of pixels and asize of a micro LED panel.

FIG. 3 is a diagram illustrating an operation of driving a micro LEDpanel through a CMOS backplane.

FIG. 4 is a diagram referred for describing a relationship between asize of a quantum dot and a luminous color.

FIGS. 5A to 5G are diagrams illustrating a method of fabricating themicro LED display device according to the first exemplary embodiment ofthe present invention.

FIG. 6 is a cross-sectional view illustrating a micro LED display deviceaccording to a second exemplary embodiment of the present invention.

FIGS. 7A to 7H are diagrams illustrating a method of fabricating themicro LED display device according to the second exemplary embodiment ofthe present invention.

FIG. 8 is a cross-sectional view illustrating a micro LED display deviceaccording to a third exemplary embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a structure of a colorfilter related to the present invention.

FIGS. 10A to 10H are diagrams illustrating a method of fabricating themicro LED display device according to the third exemplary embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments disclosed in the presentspecification will be described in detail with reference to theaccompanying drawings, and the same or similar constituent elements aredenoted by the same reference numerals regardless of a sign of thedrawing, and repeated description thereof will be omitted. Hereinafter,in the description of the exemplary embodiments of the presentinvention, a case where each layer (film), a region, a pattern, orstructures are formed “on” or “under” a substrate, each layer (film), aregion, a pad, or patterns includes all of the cases in which each layer(film), the region, the pattern, or the structures are directly formed“on” or “under” the substrate, each layer (film), the region, the pad,or the patterns, or intervening constituent elements are present.Further, a reference of “on” or “under” each layer is described withreference to the drawings. In the drawings, for convenience andclearness of description, a thickness or a size of each layer isexaggerated, omitted, or schematically illustrated. Further, a size ofeach constituent element does not totally reflect an actual size.

In describing the exemplary embodiments disclosed in the presentspecification, a detailed explanation of known related technology may beomitted so as to avoid unnecessarily obscuring the subject matter of theexemplary embodiments disclosed in the present specification. Further,the accompanying drawings are provided for helping easy understanding ofthe exemplary embodiments disclosed in the present specification, andthe technical spirit disclosed in the present specification is notlimited by the accompanying drawings, and it will be appreciated thatthe present invention includes all of the modifications, equivalentmatters, and substitutes included in the spirit and the technical scopeof the present invention.

The present invention proposes a micro light emitting diode (LED)display device which includes a separator structure formed on a growthsubstrate or an emission structure corresponding to locations betweenpixels to implement a full color, and a method of fabricating the same.Hereinafter, in the present exemplary embodiment, the micro LED displaydevice may be formed by flip-chip bonding a micro LED panel including aplurality of micro LED pixels and a CMOS backplane including a pluralityof CMOS cells for independently driving the plurality of micro LEDpixels through bumps.

Hereinafter, various exemplary embodiments of the present invention willbe described in detail with reference to the drawings.

First Exemplary Embodiment

FIG. 1 is a cross-sectional view illustrating a micro LED display deviceaccording to a first exemplary embodiment of the present invention.

Referring to FIG. 1, the micro LED display device 100 according to thefirst exemplary embodiment of the present invention may include a microLED driving substrate (or a CMOS backplane) 130, a micro LED panel, anda plurality of bumps 135.

The micro LED panel is an LED panel including an array structure inwhich a plurality of micro LED pixels stacked on a wafer is arranged ina matrix form, and may serve to output R/G/B light corresponding toimage signals of an image display device. In this case, the plurality ofmicro LED pixels may be formed by any one of a blue LED, a green LED, ared LED, and a UV LED, but is not limited thereto.

For example, as illustrated in FIG. 2, the micro LED panel may includemicro LED pixels arranged in a plurality of rows 720 and a plurality ofcolumns 1280. Further, each of the plurality of micro LED pixelsconfiguring the micro LED panel may be formed in a size of 8 μm×8 μm.However, the micro LED display device 100 may be fabricated by changingthe number of pixels and a pixel size of the micro LED panel and thelike according to a usage and the kind of an image display device, whichis apparent to those skilled in the art.

The micro LED panel may include an emission structure (or the pluralityof micro LED pixels 120), a growth substrate 110 on the emissionstructure 120, a plurality of separators 140 on the growth substrate110, R/G/B color light changing materials 150, 160, and 170 positionedbetween the separators, and the like.

The emission structure 120 may include a first conductive semiconductorlayer, an active layer under the first conductive semiconductor layer, asecond conductive semiconductor layer under the active layer, a secondconductive metal layer under the second conductive semiconductor layer,and a first conductive metal layer under the first conductivesemiconductor layer, and a passivation layer. The emission structure 120may emit light of different wavelengths according to a composition ratioof a compound semiconductor.

The first conductive semiconductor layer may include a compoundsemiconductor of III-V group elements in which an n-type dopant isdoped. The first conductive semiconductor layer may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, AlInN, InGaN,AlN, and InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N(0≤x≤1, 0≤y≤1, 0≤x+y≤1), and an n-type dopant, such as Si, Ge, and Sn,may be doped.

The active layer is a layer in which electrons (or holes) injectedthrough the first conductive semiconductor layer and holes (orelectrons) injected through the second conductive semiconductor layermeet to emit light by a difference in a band gap of an energy bandaccording to a forming material of the active layer. The active layermay be formed in any one of a single quantum well structure, amulti-quantum well (MQW) structure, a quantum dot structure, or aquantum wire structure, but is not limited thereto. The active layer maybe formed of a semiconductor material having an empirical formula ofIn_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1). When the active layeris formed in the MQW structure, the active layer may be formed byalternately stacking a plurality of well layers and a plurality ofbarrier layers.

The second conductive semiconductor layer may include a compoundsemiconductor of III-V group elements in which a p-type dopant is doped.The second conductive semiconductor layer may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, InGaN, AlInN,AlN, InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1,0≤y≤1, 0≤x+y≤1), and a p-type dopant, such as Mg, Zn, Ca, Sr, and Ba,may be doped.

The second conductive metal layer (that is, a p electrode) may be formedon the second conductive semiconductor layer, and the first conductivemetal layer (that is, an n electrode) may be formed on the firstconductive semiconductor layer. The first and second conductive metallayers provide power to the plurality of micro LED pixels formed in themicro LED panel.

The second conductive metal layer may be disposed on the secondconductive semiconductor layer corresponding to each of the micro LEDpixels, and may be electrically connected with each CMOS cell 131provided in a micro LED driving substrate 130 through a bump 135,respectively. In the meantime, as another exemplary embodiment, when areflective layer (not illustrated), such as a distributed Braggreflector (DBR) is present on the second conductive semiconductor layer,the second conductive metal layer may be disposed on the reflectivelayer.

The first conductive metal layer may be formed on a mesa-etched regionof the first conductive semiconductor layer, and may be formed whilebeing spaced apart from the plurality of micro LED pixels by apredetermined distance. The first conductive metal layer may be formedon the first conductive semiconductor layer so as to have apredetermined width along an outer region of the micro LED panel. Aheight of the first conductive metal layer may be formed to besubstantially the same as a height of the plurality of micro LED pixels.The first conductive metal layer is electrically connected with a commoncell 132 of the micro LED driving substrate 130 by the bump 135 to serveas a common electrode of the micro LED pixels. For example, the firstconductive metal layer may be a common ground.

The passivation layer may be formed on at least one lateral surface ofthe first conductive semiconductor layer, the active layer, the secondconductive semiconductor layer, and the first and second conductivemetal layers. The passivation layer may be formed to electricallyprotect the first conductive semiconductor layer, the active layer, andthe second conductive semiconductor layer, and may be formed of, forexample, SiO₂, SiO_(x), SiO_(x)N_(y), Si₃N₄, Al₂O₃, but is not limitedthereto.

The growth substrate 110 may be formed of at least one of materialshaving transparency, for example, sapphire (Al₂O₃), a single crystalsubstrate, SiC, GaAs, GaN, ZnO, AlN, Si, GaP, InP, and Ge, but is notlimited thereto.

The plurality of separators (or partitions or barrier ribs) 140 may beformed on a flat surface, on which the emission structure 120 is notstacked, between two surfaces of the growth substrate 110. The pluralityof separators 140 may be disposed on the growth substrate 110corresponding to locations (that is, regions in which the active layerand the second conductive semiconductor layer are etched) between pixelsto minimize color mixing between the pixels. The plurality of separators140 may be fabricated by a photolithography process. Accordingly, theplurality of separators 140 may be formed of a photo resist (PR). The PRrefers to a material which is selectively removing a portion whichreceives light and a portion which does not receive light during asubsequent development processing process by using a characteristic inwhich the PR receives light at a specific wavelength, so that solubilityof the PR in a developer is changed. As the PR, a polymer compound maybe used, but the PR is not limited thereto. In the meantime, as anotherexemplary embodiment, the plurality of separators 140 may also be formedof a ceramic material, not the polymer compound. In this case, the wetor dry etching process may be added to the photolithography process.

Heights of the separators 140 may be formed to be almost the same, and agap between the separators 140 may be formed to be the same as a size ofthe pixel.

The R/G/B color light changing materials (or the R/G/B fluorescentsubstances) 150, 160, and 170 may be disposed between the separators tochange wavelengths of light emitted from the LEDs (that is, the pixels),respectively. The R/G/B color light changing materials 150, 160, and 170used in the micro LED panel 100 may be changed according to the kind ofwavelength emitted by the LED.

As the red emitting fluorescent substance 150, GaAlAs, (Y, Gd)BO₃:Eu³⁺,Y₂O₂:Eu, and the like may be used, but the red emitting fluorescentsubstance 150 is not limited thereto. As the green emitting fluorescentsubstance 160, GaP:N, Zn₂SiO₄:Mn, ZnS:Cu, Al, and the like may be used,but the green emitting fluorescent substance 160 is not limited thereto.As the blue emitting fluorescent substance 170, GaN, BaMgAl₁₄O₂₃:Eu²⁺,ZnS:Ag, and the like may be used, but the blue emitting fluorescentsubstance 170 is not limited thereto.

As the R/G/B color light changing materials 150, 160, and 170, a quantumdot may be used. The quantum dot is a semiconductor nano particle ofwhich a diameter has a size of several nanometers (nm), and has aquantum mechanics characteristic, such as a quantum confinement effect.Herein, the quantum confinement effect means a phenomenon in which as asize of a semiconductor nano particle is decreased, a band gap energy isincreased (inversely, a wavelength is decreased). The quantum dotfabricated by a chemical synthesis process may implement a desired coloronly by adjusting a particle size without changing a material thereof.For example, as illustrated in FIG. 4, according to the quantumconfinement effect, as a size of a nano particle is small, a quantum dotmay emit blue light having a short wavelength, and as a size of a nanoparticle is large, a quantum dot may emit red light having a longwavelength.

The quantum dot may be a II-VI, III-V, or IV group material, andparticularly, may be CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, InP, GaP, GaInP₂,PbS, ZnO, TiO₂, AgI, AgBr, Hg₁₂, PbSe, In₂S₃, In₂Se₃, Cd₃P₂, Cd₃As₂, orGaAs. Further, the quantum dot may have a core-shell structure. Herein,a core may include any one material selected from the group consistingof CdSe, CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe, and HgS, and a shell mayinclude any one material selected from the group consisting of CdSe,CdTe, CdS, ZnSe, ZnTe, ZnS, HgTe, and HgS.

The micro LED driving substrate 130 may be disposed so as to face themicro LED panel, and may serve to drive the plurality of micro LEDpixels provided in the micro LED panel in response to an input imagesignal.

The micro LED driving substrate 130 may include an active matrix circuitunit including the plurality of CMOS cells 131 for individually drivingthe plurality of micro LED pixels, and a common cell 132 disposed in anouter region of the active matrix circuit unit. Examples of the microLED driving substrate 130 may include a silicon (Si) substrate or a PCBsubstrate, but the micro LED driving substrate 130 is not limitedthereto.

Each of the plurality of CMOs cells 131 provided in the active matrixcircuit unit is electrically connected to the corresponding micro LEDpixel through the bump 135. Each of the plurality of CMOs cells 131 isan integrated circuit (IC) for individually driving the correspondingmicro LED pixel. Accordingly, each of the plurality of CMOS cells 131may be a pixel driving circuit including two transistors and onecapacitor, and when the micro LED panel is flip-chip bonded to the microLED driving substrate 130 by using the bumps 135, each of the pluralityof CMOS cells 131 may be configured in a form in which the individualmicro LED pixel is disposed between a drain terminal and a common groundterminal of the transistor of the pixel driving circuit according to theequivalent circuit.

The common cell 132 disposed in the outer region of the active matrixcircuit unit may include a data driver IC and a scan driver IC. Forexample, as illustrated in FIG. 3, the plurality of micro LED pixels(not illustrated) configuring the micro LED panel may be positioned atcrossing points of a plurality of scanning lines 325 and a plurality ofdata lines 315. The plurality of scanning lines 325 input to theplurality of micro LED pixels are controlled by the scan driver IC 320,and the plurality of data lines 315 input to the plurality of micro LEDpixels are controlled by the data driver IC 310.

A control operation of the micro LED panel through the micro LED drivingsubstrate 130 will be simply described. The scan driver IC 320 turns onthe pixel by inputting a high (H) signal to any one or more of theplurality of scanning lines 325 while scanning all of the plurality ofscanning lines 325 when providing image data. In the meantime, when thedata driver IC 310 provides image data to the plurality of data lines315, the pixels which are in a turn-on state in the scanning lines allowthe image data to pass through and the corresponding image data isdisplayed through the micro LED panel. By this manner, a display for oneframe is completed while all of the scanning lines are sequentiallyscanned.

As described above, in the micro LED display device according to thefirst exemplary embodiment of the present invention, the plurality ofseparators is periodically disposed on the growth substratecorresponding to the locations between the pixels, thereby effectivelyremoving color interference between the pixels and easily applying theR/G/B color light changing materials onto the growth substrate.

FIGS. 5A to 5G are diagrams illustrating a method of fabricating themicro LED display device according to the first exemplary embodiment ofthe present invention.

Referring to FIG. 5A, the emission structure 120 may be formed bysequentially growing the first conductive semiconductor layer 121, theactive layer 122, and the second conductive semiconductor layer 123 onthe growth substrate 110.

The growth substrate 110 may be formed of at least one of materialshaving transparency, for example, sapphire (Al₂O₃), a single crystalsubstrate, SiC, GaAs, GaN, ZnO, AlN, Si, GaP, InP, and Ge, but is notlimited thereto.

The first conductive semiconductor layer 121 may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, AlInN, InGaN,AlN, and InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N(0≤x≤1, 0≤y≤1, 0≤x+y≤1), and an n-type dopant, such as Si, Ge, and Sn,may be doped. The first conductive semiconductor layer 121 may be formedby injecting trimethyl gallium (TMGa) gas, ammonia (NH₃) gas, and xylene(SiH₄) gas to a chamber together with hydrogen gas. An undopedsemiconductor layer (not illustrated) and/or a buffer layer (notillustrated) may be further included between the growth substrate 110and the first conductive semiconductor layer 121, but the presentinvention is not limited thereto.

The active layer 122 may be formed of a semiconductor material having anempirical formula of In_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).The active layer 122 may be formed by injecting trimethyl gallium (TMGa)gas, trimethyl indium (TMIn) gas, and ammonia (NH₃) gas to a chambertogether with hydrogen gas.

The second conductive semiconductor layer 123 may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, InGaN, AlInN,AlN, InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1,0≤y≤1, 0≤x+y≤1), and a p-type dopant, such as Mg, Zn, Ca, Sr, and Ba,may be doped. The second conductive semiconductor layer 123 may beformed by injecting trimethyl gallium (TMGa) gas, ammonia (NH₃) gas, andbiacetyl cyclopentadienyl magnesium (EtCp₂Mg){Mg(C₂H₅C₅H₄)₂} gas to achamber together with hydrogen gas.

Referring to FIG. 5B, a plurality of LEDs (that is, the plurality ofmicro LED pixels) may be formed by performing isolation etching on theemission structure 120 according to a unit pixel region. For example,the isolation etching may be performed by a dry etching method, such asinductively coupled plasma (ICP). One upper surface of the firstconductive semiconductor layer 121 is exposed through the isolationetching. In this case, in order to form the common electrode (that is,the n electrode) 125, the emission structure 120 may be etched so asthat a border region of the first conductive semiconductor layer 121 hasa predetermined width.

Referring to FIG. 5C, the second conductive metal layer 124 may beformed on one upper surface of the second conductive semiconductor layer123, and the first conductive metal layer 125 may be formed on one uppersurface of the mesa etched first conductive semiconductor layer 121. Inthis case, the first and second conductive metal layers 125 and 124 maybe formed by a deposition process or a plating process, but are notlimited thereto.

Then, a passivation layer 126 may be formed on the growth substrate 110,the compound semiconductor layers 121, 122, and 123, the firstconductive metal layer 125, and the second conductive metal layer 124,and the passivation layer 126 may be selectively removed so that oneupper surface of each of the first and second conductive metal layers125 and 124 is exposed to the outside.

Referring to FIG. 5D, the plurality of bumps 135 is disposed on the CMOScells 131 and the common cell 132 of the micro LED driving substrate130. The first and second conductive metal layers 125 and 124 are madeto head downwardly by inversing up and down the micro LED panel. TheCMOS cells 131 are in contact with the micro LED pixels by making themicro LED driving substrate 130 in the state in which the plurality ofbumps 135 is disposed face the micro LED panel and correspondingone-to-one the CMOS cells 131 and the micro LED pixels, and then theCMOS cells 131 and the micro LED pixels are heated. Then, the pluralityof bumps 135 is melted, and as a result, the CMOS cells 131 and thecorresponding micro LED pixels are electrically connected, and thecommon cell 132 of the micro LED driving substrate 130 and the commonelectrode 125 of the micro LED panel corresponding to the common cell132 are electrically connected.

Referring to FIG. 5E, the PR 140 may be coated on the growth substrate110 by using a spin coating method. In the meantime, as anotherexemplary embodiment, bonding force between the growth substrate 110 andthe PR 140 may be improved by chemically processing (for example,hexamethyldisilazane processing) the surface of the growth substrate 110before the coating process.

Then, mask patterns 180 may be precisely arranged on the PR 140, andthen an exposure process of emitting ultraviolet rays and the like maybe performed. In this case, the mask patterns 180 may be arranged in amatrix form, and an interval between the mask patterns 180 maycorrespond to a distance between the pixels.

Referring to FIG. 5F, the plurality of separators 140 may be formed onthe growth substrate 110 by performing a developing process on the PR140 which passes the exposure process. In this case, the plurality ofseparators 140 may be disposed on the growth substrate 110 correspondingto the locations between the pixels (that is, the regions in which theactive layer and the second conductive semiconductor layer are etched).In the developing process, as a developer for the PR 140, awater-soluble alkali solution may be used.

In the meantime, in the present exemplary embodiment, the case where theplurality of separators is formed through the PR is exemplified, but thepresent invention is not limited thereto. For example, as anotherexemplary embodiment, the plurality of separators may also be formed onthe growth substrate by forming a material for forming the separator onthe growth substrate, stacking the PR on the material, sequentiallyperforming exposure and developing processes by using a mask pattern,and wet or dry etching a region exposed by the PR.

Referring to FIG. 5G, the R fluorescent substance 150 may be injectedbetween a first separator and a second separator formed on the growthsubstrate 110, the G fluorescent substance 160 may be injected betweenthe second separator and a third separator formed on the growthsubstrate 110, and the B fluorescent substance 170 may be injectedbetween the third separator and a fourth separator formed on the growthsubstrate 110. Accordingly, the pixel in which the R fluorescentsubstance 150 is present between the separators may emit red light, thepixel in which the G fluorescent substance 160 is present between theseparators may emit green light, and the pixel in which the Bfluorescent substance 170 is present between the separators may emitblue light.

The micro LED display device 100 formed through the foregoing processesmay implement a full color of high resolution (an HD level). The microLED display device 100 may be applied to various display devices, suchas a head-up display (HUD) for a vehicle and a head mounted display(HMD).

Second Exemplary Embodiment

FIG. 6 is a cross-sectional view illustrating a micro LED display deviceaccording to a second exemplary embodiment of the present invention.Unlike the micro LED display device 100 of FIG. 1, the exemplaryembodiment of the present invention may provide a micro LED displaydevice which is capable of minimizing light scattering by removing agrowth substrate. Herein, in the present exemplary embodiment, a microLED driving substrate 230, an emission structure 220, a plurality ofseparators 240, and R/G/B color light changing materials 250, 260, and270 are the same as the micro LED driving substrate 130, the emissionstructure 120, the plurality of separators 140, and the R/G/B colorlight changing materials 150, 160, and 170 of FIG. 1, so that detaileddescriptions thereof will be omitted.

Referring to FIG. 6, the micro LED display device 200 according to thesecond exemplary embodiment of the present invention may include themicro LED driving substrate 230, a micro LED panel, and a plurality ofbumps 235.

The micro LED panel is an LED panel including an array structure inwhich a plurality of micro LED pixels stacked on a wafer is arranged ina matrix form, and may serve to output R/G/B light corresponding toimage signals of an image display device. In this case, the plurality ofmicro LED pixels may be formed by any one of a blue LED, a green LED, ared LED, and a UV LED, but is not limited thereto.

The micro LED panel may include the emission structure (or the pluralityof micro LED pixels) 220, the plurality of separators 240 on theemission structure 220, and the R/G/B color light changing materials250, 260, and 270 positioned between the separators, and the like.

The emission structure 220 may include a first conductive semiconductorlayer, an active layer, a second conductive semiconductor layer, a firstconductive metal layer, a second conductive metal layer, and apassivation layer. The emission structure 220 may emit light ofdifferent wavelengths according to a composition ratio of a compoundsemiconductor.

The second conductive metal layer (that is, a p electrode) may be formedon the second conductive semiconductor layer of the emission structure220, and the first conductive metal layer (that is, an n electrode) maybe formed on the first conductive semiconductor layer. A passivationlayer may be formed on at least one lateral surface of the firstconductive semiconductor layer, the active layer, the second conductivesemiconductor layer, and the first and second conductive metal layers.The passivation layer may be formed to electrically protect the firstconductive semiconductor layer, the active layer, and the secondconductive semiconductor layer, and may be formed of, for example, SiO₂,SiO_(x), SiO_(x)N_(y), Si₃N₄, Al₂O₃, but is not limited thereto.

The plurality of separators 240 may be formed on a flat surface which isnot etched between two surfaces of the emission structure 220. Theplurality of separators 240 may be disposed on the emission structure220 corresponding to locations (that is, the regions in which the activelayer and the second conductive semiconductor layer are etched) betweenthe pixels to serve to minimize color mixing between the pixels. Theplurality of separators 240 may be fabricated by a photolithographyprocess.

Heights of the separators 240 may be formed to be almost the same, and agap between the separators 240 may be formed to be the same as a size ofthe pixel.

The R/G/B color light changing materials (or the R/G/B fluorescentsubstances) 250, 260, and 270 may be disposed between the separators tochange wavelengths of light emitted from the LEDs (that is, the pixels),respectively. As the red emitting fluorescent substance 250, GaAlAs, (Y,Gd)BO₃:Eu³⁺, Y₂O₂:Eu, a quantum dot, and the like may be used, but thered emitting fluorescent substance 250 is not limited thereto. As thegreen emitting fluorescent substance 260, GaP:N, Zn₂SiO₄:Mn, ZnS:Cu, Al,a quantum dot, and the like may be used, but the green emittingfluorescent substance 260 is not limited thereto. As the blue emittingfluorescent substance 270, GaN, BaMgAl₁₄O₂₃:Eu²⁺, ZnS:Ag, a quantum dot,and the like may be used, but the blue emitting fluorescent substance270 is not limited thereto.

The micro LED driving substrate 230 may be disposed so as to face themicro LED panel, and may serve to drive the plurality of micro LEDpixels provided in the micro LED panel in response to an input imagesignal. The micro LED driving substrate 230 may include an active matrixcircuit unit including a plurality of CMOS cells 231 for individuallydriving the plurality of micro LED pixels, and a common cell 232disposed in an outer region of the active matrix circuit unit.

As described above, in the micro LED display device according to thesecond exemplary embodiment of the present invention, the plurality ofseparators is periodically disposed on the emission structurecorresponding to the locations between the pixels, thereby effectivelyremoving color interference between the pixels, minimizing lightscattering due to the growth substrate, and easily applying the R/G/Bcolor light changing materials onto the emission structure.

FIGS. 7A to 7G are diagrams illustrating a method of fabricating themicro LED display device according to the second exemplary embodiment ofthe present invention.

Referring to FIG. 7A, the emission structure 220 may be formed bysequentially growing a first conductive semiconductor layer 221, anactive layer 222, and a second conductive semiconductor layer 223 on agrowth substrate 210.

The growth substrate 210 may be formed of at least one of the materialshaving transparency, for example, sapphire (Al₂O₃), a single crystalsubstrate, SiC, GaAs, GaN, ZnO, AlN, Si, GaP, InP, and Ge, but is notlimited thereto.

The first conductive semiconductor layer 221 may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, AlInN, InGaN,AlN, and InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N(0≤x≤1, 0≤y≤1, 0≤x+y≤1), and an n-type dopant, such as Si, Ge, and Sn,may be doped. The first conductive semiconductor layer 221 may be formedby injecting trimethyl gallium (TMGa) gas, ammonia (NH₃) gas, and xylene(SiH₄) gas to a chamber together with hydrogen gas.

The active layer 222 may be formed of a semiconductor material having anempirical formula of In_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).The active layer 222 may be formed by injecting trimethyl gallium (TMGa)gas, trimethyl indium (TMIn) gas, and ammonia (NH₃) gas to a chambertogether with hydrogen gas.

The second conductive semiconductor layer 223 may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, InGaN, AlInN,AlN, InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1,0≤y≤1, 0≤x+y≤1), and a p-type dopant, such as Mg, Zn, Ca, Sr, and Ba,may be doped. The second conductive semiconductor layer 223 may beformed by injecting trimethyl gallium (TMGa) gas, ammonia (NH₃) gas, andbiacetyl cyclopentadienyl magnesium (EtCp₂Mg){Mg(C₂H₅C₅H₄)₂} gas to achamber together with hydrogen gas.

Referring to FIG. 7B, a plurality of LEDs (that is, the plurality ofmicro LED pixels) may be formed by performing isolation etching on theemission structure 220 according to a unit pixel region. For example,the isolation etching may be performed by a dry etching method, such asinductively coupled plasma (ICP). One upper surface of the firstconductive semiconductor layer 221 is exposed through the isolationetching. Referring to FIG. 7C, the second conductive metal layer 224 maybe formed on one upper surface of the second conductive semiconductorlayer 223, and the first conductive metal layer 225 may be formed on oneupper surface of the mesa-etched first conductive semiconductor layer221. In this case, the first and second conductive metal layers 225 and224 may be formed by a deposition process or a plating process, but arenot limited thereto.

Then, a passivation layer 226 may be formed on the growth substrate 210,the compound semiconductor layers 221, 222, and 223, the firstconductive metal layer 225, and the second conductive metal layer 224,and the passivation layer 226 may be selectively removed so that oneupper surface of each of the first and second conductive metal layers225 and 224 is exposed to the outside.

Referring to FIG. 7D, the plurality of bumps 235 is disposed on the CMOScells 231 and the common cell 232 of the micro LED driving substrate230. The first and second conductive metal layers 225 and 224 are madeto head downwardly by inversing up and down the micro LED panel. TheCMOS cells 231 are in contact with the micro LED pixels by making themicro LED driving substrate 230 in the state in which the plurality ofbumps 235 is disposed face the micro LED panel and correspondingone-to-one the CMOS cells 231 and the micro LED pixels, and then theCMOS cells 231 and the micro LED pixels are heated. Then, the pluralityof bumps 235 is melted, and as a result, the CMOS cells 231 and thecorresponding micro LED pixels are electrically connected, and thecommon cell 232 of the micro LED driving substrate 230 and the commonelectrode 225 of the micro LED panel corresponding to the common cell232 are electrically connected.

Referring to FIG. 7E, the growth substrate 210 attached to the emissionstructure 220 may be separated by a laser lift off (LLO) method, achemical lift off (CLO) method, an electrical lift off (ELO), an etchingmethod, or the like. As another exemplary embodiment, the growthsubstrate 210 attached to the emission structure 220 may be ground to beflat and at least a part of the growth substrate 210 may be removed.

Referring to FIG. 7F, an upper portion of the emission structure 220 maybe coated with a photo resist (PR) 240 by using a spin coating method.In the meantime, as another exemplary embodiment, bonding force betweenthe emission structure 220 and the PR 240 may be improved by chemicallyprocessing (for example, hexamethyldisilazane processing) the surface ofthe emission structure 220 before the coating process. Further, apassivation layer (not illustrated) for protecting the emissionstructure 220 may be formed between the emission structure 220 and thePR 240 before the coating process. Then, mask patterns 280 may beprecisely arranged on the PR 240 and then an exposure process ofemitting ultraviolet rays and the like may be performed.

Referring to FIG. 7G, the plurality of separators 240 may be formed onthe emission structure 220 by performing a developing process on the PR240 which passes the exposure process. In this case, the plurality ofseparators 240 may be disposed on the emission structure 220corresponding to the locations between the pixels (that is, the regionsin which the active layer and the second conductive semiconductor layerare etched).

In the meantime, in the present exemplary embodiment, the case where theplurality of separators is formed through the PR is exemplified, but thepresent invention is not limited thereto. For example, as anotherexemplary embodiment, the plurality of separators may also be formed onthe growth substrate by forming a material for forming the separator onthe growth substrate, stacking the PR on the material, sequentiallyperforming exposure and developing processes by using a mask pattern,and wet or dry etching a region exposed by the PR.

Referring to FIG. 7H, the R fluorescent substance 250 may be injectedbetween a first separator and a second separator formed on the emissionstructure 220, the G fluorescent substance 260 may be injected betweenthe second separator and a third separator formed on the emissionstructure 220, and the B fluorescent substance 270 may be injectedbetween the third separator and a fourth separator formed on theemission structure 220. Accordingly, the pixel in which the Rfluorescent substance 250 is present between the separators may emit redlight, the pixel in which the G fluorescent substance 260 is presentbetween the separators may emit green light, and the pixel in which theB fluorescent substance 270 is present between the separators may emitblue light.

The micro LED display device 200 formed through the foregoing processesmay minimize light scattering due to the growth substrate and implementa full color of high resolution (an HD level).

Third Exemplary Embodiment

FIG. 8 is a cross-sectional view illustrating a micro LED display deviceaccording to a third exemplary embodiment of the present invention.Unlike the micro LED display device 200 of FIG. 6, the exemplaryembodiment of the present invention may provide a micro LED displaydevice which is capable of implementing a full color by disposingfluorescent substances and color filters between separators.Hereinafter, in the present exemplary embodiment, a micro LED drivingsubstrate 330, an emission structure 320, and a plurality of separators340 are the same as the micro LED driving substrate 230, the emissionstructure 220, and the plurality of separators 240 of FIG. 6, so thatdetailed descriptions thereof will be omitted.

Referring to FIG. 8, the micro LED display device 300 according to thethird exemplary embodiment of the present invention may include themicro LED driving substrate 330, a micro LED panel, and a plurality ofbumps 335.

The micro LED panel is an LED panel including an array structure inwhich a plurality of micro LED pixels stacked on a wafer is arranged ina matrix form, and may serve to output R/G/B light corresponding toimage signals of an image display device. In this case, the plurality ofmicro LED pixels may be formed by any one of a blue LED, a green LED, ared LED, and a UV LED, but is not limited thereto.

The micro LED panel may include an emission structure (or a plurality ofmicro LED pixels) 320, the plurality of separators 340 on the emissionstructure 320, a fluorescent substance 350 positioned between theseparators, and color filters 360, 370, and 380 on the fluorescentsubstance 350.

The plurality of separators 340 may be formed on a flat surface which isnot etched between two surfaces of the emission structure 320. Theplurality of separators 340 may be disposed on the emission structure320 corresponding to locations (that is, the regions in which an activelayer and a second conductive semiconductor layer are etched) betweenthe pixels to serve to minimize color mixing between the pixels. Theplurality of separators 340 may be fabricated by a photolithographyprocess.

Heights of the separators 340 may be formed to be almost the same, and agap between the separators 340 may be formed to be the same as a size ofthe pixel.

The fluorescent substance 350 may be disposed between the separators 340on the emission structure 320 to change a wavelength of light emittedfrom the plurality of micro LED pixels to a wavelength of white light.For example, when the emission structure 320 is a blue LED, a yellowfluorescent substance (a material based on Y3Al5O12:Ce (YAG:Ce)) may beused as the fluorescent substance. Further, when the emission structure320 is a blue LED, a fluorescent substance obtained by mixing a greenfluorescent substance and a red fluorescent substance may be used as thefluorescent substance. Further, when the emission structure 320 is a UVLED, a fluorescent substance obtained by mixing a blue fluorescentsubstance, a green fluorescent substance, and a red fluorescentsubstance may be used as the fluorescent substance.

The color filters 360, 370, and 380 may be attached on the fluorescentsubstance 350 in the unit of a pixel to transmit only light of aspecific wavelength in white light emitted from the fluorescentsubstance 350. That is, the R filter 360 may transmit only a wavelengthof red light in white light emitted from the fluorescent substance 350,the G filter 370 may transmit only a wavelength of green light in whitelight emitted from the fluorescent substance 350, and the B filter 380may transmit only a wavelength of blue light in white light emitted fromthe fluorescent substance 350. Accordingly, the pixel in which thefluorescent substance 350 and the R filter 360 are present between theseparators may emit red light, the pixel in which the fluorescentsubstance 350 and the G filter 370 are present between the separatorsmay emit green light, and the pixel in which the fluorescent substance350 and the B filter 380 are present between the separators may emitblue light.

As the exemplary embodiment, as illustrated in FIG. 9, a color filter900 according to the present invention may include a transparentsubstrate 910, a black matrix 920, color filter layers 930, 940, and950, an over coat layer 960, and an ITO layer 970.

The transparent substrate 910 may be formed of thin glass or plastic.The black matrix 920 is disposed on the transparent substrate 910 tomake light be positioned in an optically inactive region of thetransparent substrate 910 to protect light from being leaked. The blackmatrix 920 needs to have low reflectance for an optimum contrast. Theblack matrix 920 may be formed of an inorganic material or an organicmaterial, and chrome Cr may be used.

The color filter layers 930, 940, and 950 may be disposed on thetransparent substrate 910 and include R/G/B dyes or pigments. The overcoat layer 960 protects the color filter layers 930, 940, and 950 fromimpurities and flattens a surface of the color filter 900. The over coatlayer 960 may be formed of a transparent acryl resin, a polyimide resin,a polyurethane resin, or the like. The ITO layer 970 may be formed onthe over coat layer 960.

The micro LED driving substrate 330 may be disposed so as to face themicro LED panel, and may serve to drive the plurality of micro LEDpixels provided in the micro LED panel in response to an input imagesignal. The micro LED driving substrate 330 may include an active matrixcircuit unit including a plurality of CMOS cells 331 for individuallydriving the plurality of micro LED pixels, and a common cell 332disposed in an outer region of the active matrix circuit unit.

As described above, in the micro LED display device according to thethird exemplary embodiment of the present invention, the plurality ofseparators is periodically disposed on the emission structurecorresponding to the locations between the pixels, thereby effectivelyremoving color interference between the pixels, minimizing lightscattering due to the growth substrate, and easily applying thefluorescent substance for emitting white light onto the emissionstructure.

FIGS. 10A to 10G are diagrams illustrating a method of fabricating themicro LED display device according to the third exemplary embodiment ofthe present invention.

Referring to FIG. 10A, the emission structure 320 may be formed bysequentially growing a first conductive semiconductor layer 321, anactive layer 322, and a second conductive semiconductor layer 323 on agrowth substrate 310.

The growth substrate 310 may be formed of at least one of materialshaving transparency, for example, sapphire (Al₂O₃), a single crystalsubstrate, SiC, GaAs, GaN, ZnO, AlN, Si, GaP, InP, and Ge, but is notlimited thereto.

The first conductive semiconductor layer 321 may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, AlInN, InGaN,AlN, and InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N(0≤x≤1, 0≤y≤1, 0≤x+y≤1), and an n-type dopant, such as Si, Ge, and Sn,may be doped. The first conductive semiconductor layer 321 may be formedby injecting trimethyl gallium (TMGa) gas, ammonia (NH₃) gas, and xylene(SiH₄) gas to a chamber together with hydrogen gas.

The active layer 322 may be formed of a semiconductor material having anempirical formula of In_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1, 0≤y≤1, 0≤x+y≤1).The active layer 322 may be formed by injecting trimethyl gallium (TMGa)gas, trimethyl indium (TMIn) gas, and ammonia (NH₃) gas to a chambertogether with hydrogen gas.

The second conductive semiconductor layer 323 may be selected fromsemiconductor materials, for example, InAlGaN, GaN, AlGaN, InGaN, AlInN,AlN, InN, having an empirical formula of In_(x)Al_(y)Ga_(1−x−y)N (0≤x≤1,0≤y≤1, 0≤x+y≤1), and a p-type dopant, such as Mg, Zn, Ca, Sr, and Ba,may be doped. The second conductive semiconductor layer 323 may beformed by injecting trimethyl gallium (TMGa) gas, ammonia (NH₃) gas, andbiacetyl cyclopentadienyl magnesium (EtCp₂Mg){Mg(C₂H₅C₅H₄)₂} gas to achamber together with hydrogen gas.

Referring to FIG. 10B, a plurality of LEDs (that is, the plurality ofmicro LED pixels) may be formed by performing isolation etching on theemission structure 320 according to a unit pixel region. For example,the isolation etching may be performed by a dry etching method, such asinductively coupled plasma (ICP). One upper surface of the firstconductive semiconductor layer 321 is exposed through the isolationetching.

Referring to FIG. 10C, the second conductive metal layer 324 may beformed on one upper surface of the second conductive semiconductor layer323, and the first conductive metal layer 325 may be formed on one uppersurface of the mesa-etched first conductive semiconductor layer 321. Inthis case, the first and second conductive metal layers 324 and 325 maybe formed by a deposition process or a plating process, but are notlimited thereto. Then, a passivation layer 326 may be formed on thegrowth substrate 310, the compound semiconductor layers 321, 322, and323, and the first and second conductive metal layer 325 and 324, andthe passivation layer 326 may be selectively removed so that one uppersurface of each of the first and second conductive metal layers 325 and324 are exposed to the outside.

Referring to FIG. 10D, a plurality of bumps 335 is disposed on the CMOScells 331 and the common cell 332 of the micro LED driving substrate330. The first and second conductive metal layers 325 and 324 are madeto head downwardly by inversing up and down the micro LED panel. TheCMOS cells 331 are in contact with the micro LED pixels by making themicro LED driving substrate 330 in the state in which the plurality ofbumps 335 is disposed face the micro LED panel and correspondingone-to-one the CMOS cells 331 and the micro LED pixels, and then theCMOS cells 331 and the micro LED pixels are heated. Then, the pluralityof bumps 335 is melted, and as a result, the CMOS cells 331 and thecorresponding micro LED pixels are electrically connected, and thecommon cell 332 of the micro LED driving substrate 330 and the commonelectrode 325 of the micro LED panel corresponding to the common cell332 are electrically connected.

Referring to FIG. 10E, the growth substrate 310 attached to the emissionstructure 320 may be separated by a laser lift off (LLO) method, achemical lift off (CLO) method, an electrical lift off (ELO), an etchingmethod, or the like.

Referring to FIG. 10F, an upper surface of the emission structure 320may be coated with a photo resist (PR) 340 by using a spin coatingmethod. In the meantime, as another exemplary embodiment, bonding forcebetween the emission structure 320 and the PR 340 may be improved bychemically processing (for example, hexamethyldisilazane processing) thesurface of the emission structure 320 before the coating process.Further, a passivation layer (not illustrated) for protecting theemission structure 320 may be formed between the emission structure 320and the PR 340 before the coating process. Then, mask patterns 380 maybe precisely arranged on the PR 340 and then an exposure process ofemitting ultraviolet rays and the like may be performed.

Referring to FIG. 10G, the plurality of separators 340 may be formed onthe emission structure 320 by performing a developing process on the PR340 which passes the exposure process. In this case, the plurality ofseparators 340 may be disposed on the emission structure 320corresponding to the locations between the pixels (that is, the regionsin which the active layer and the second conductive semiconductor layerare etched).

In the meantime, in the present exemplary embodiment, the case where theplurality of separators is formed through the PR is exemplified, but thepresent invention is not limited thereto. For example, as anotherexemplary embodiment, the plurality of separators may also be formed onthe growth substrate by forming a material for forming the separator onthe growth substrate, stacking the PR on the material, sequentiallyperforming exposure and developing processes by using a mask pattern,and wet or dry etching a region exposed by the PR.

Referring to FIG. 10H, the fluorescent substance 350 may be injectedbetween the separators 340 formed on the emission structure 320.Accordingly, the fluorescent substance 350 may change a wavelength oflight emitted from the micro LED pixel to a wavelength of white light.

Then, the color filters 360, 370, and 380 may be formed (or attached) onthe plurality of separators 340 and the fluorescent substance 350.Accordingly, the R filter 360 among the color filters may transmit onlya wavelength of red light in white light emitted from the fluorescentsubstance 350, the G filter 370 may transmit only a wavelength of greenlight in white light emitted from the fluorescent substance 350, and theB filter 380 may transmit only a wavelength of blue light in white lightemitted from the fluorescent substance 350.

The micro LED display device 300 formed through the foregoing processesmay minimize light scattering due to the growth substrate and implementa full color of high resolution (an HD level).

In the meantime, in the foregoing, the particular exemplary embodimentsof the present invention have been described, but may be variouslymodified without departing from the scope of the invention as a matterof course. Accordingly, the scope of the present invention is notlimited to the exemplary embodiment, and should be defined inequivalents of the claims, as well as the claims to be described below.

What is claimed is:
 1. A micro-LED display comprising: a micro-LED panelincluding an emission structure having a first surface formed of aplurality of micro-LED pixels arranged in rows and columns and a secondsurface formed of a plurality of separators having at least a firstseparator, a second separator, a third separator and a fourth separator;a micro-LED driving substrate including a plurality of CMOS cells forindividually driving the plurality of micro-LED pixels; and afluorescent substance having a first color changing material between thefirst separator and the second separator, a second color changingmaterial between the second separator and the third separator and athird color changing material between the third separator and the fourthseparator; wherein the plurality of micro LED pixels are formed byetching a first surface of the emission structure in predetermined etchportions, and the plurality of separators are formed in correspondenceto the etch portions.
 2. The micro-LED display of claim 1, wherein eachof the separators is formed about the same height and a gap between theseparators is formed to be about the same size as a size of themicro-LED pixel.
 3. The micro-LED display of claim 1, wherein theplurality of micro LED pixels comprise at least a first micro-LED pixel,a second micro-LED pixel, and a third micro-LED pixel and the firstcolor changing material, the second color changing material and thethird color changing material forming the second surface incorrespondence to the first micro-LED pixel, the second micro-LED pixel,and the third micro-LED pixel, respectively.
 4. The micro-LED display ofclaim 1, wherein the plurality of separators are formed of a polymercompound or a ceramic material.
 5. The micro-LED display of claim 1,wherein the first, second, and third color changing materials includequantum dots.
 6. The micro-LED display of claim 1, wherein the first,second, and third color changing matarials have the same height as aheight of the separator.
 7. The micro-LED display of claim 1, whereinthe plurality of separators are formed on an upper surface of the firstconductive semiconductor layer in a direction corresponding to thesecond surface of the emission structure.
 8. A micro-LED displaycomprising: a micro-LED panel including an emission structure having afirst surface formed of a plurality of micro-LED pixels arranged in rowsand of columns and a second surface formed of a plurality of separatorshaving at least a first separator, a second separator, a third separatorand a fourth separator; a micro-LED driving substrate including aplurality of CMOS cells for individually driving the plurality ofmicro-LED pixels; a fluorescent substance having a first color changingmaterial between the first separator and the second separator, a secondcolor changing material between the second separator and the thirdseparator and a third color changing material between the thirdseparator and the fourth separator; and a plurality of color filershaving a red color filer covering the first color changing material, agreen color filter covering the second color changing material and ablue color filter covering the third color changing material; whereinthe first color changing material, the second changing material and thethird changing material are formed of same material and change awavelength of blue or UV light to a wavelength of white light.
 9. Themicro-LED display of claim 8, wherein the first, second, and third colorchanging materials have the same height as a height of the separator.10. The micro-LED display of claim 8, wherein the plurality of micro LEDpixels are formed by etching a first surface of the emission structurein predetermined etch portions, and the plurality of separators areformed in correspondence to the etch portions.
 11. The micro-LED displayof claim 8, wherein the first, second, and third color changingmaterials include quantum dots.
 12. The micro-LED display of claim 8,wherein the plurality of separators are formed on an upper surface ofthe first conductive semiconductor layer in a direction corresponding tothe second surface of the emission structure.
 13. The micro-LED displayof claim 8, wherein the plurality of separators are formed of a polymercompound or a ceramic material.
 14. A micro-LED display comprising: amicro-LED panel including an emission structure having a first surfaceformed of a plurality of micro-LED pixels arranged in rows and ofcolumns and a second surface formed of a plurality of separators havingat least a first separator, a second separator, a third separator and afourth separator; a micro-LED driving substrate including a plurality ofCMOS cells for individually driving the plurality of micro-LED pixels; afluorescent substance mixed a red color changing material, a green colorchanging material and a blue color changing material and formed betweenthe first separator and the second separator, between the secondseparator and the third separator and between the third separator andthe fourth separator; and a plurality of color filers having a red colorfiler covering the fluorescent substance between the first separator andthe second separator, a green color filer covering the fluorescentsubstance of between the second separator and the third separator and ablue color filter covering the fluorescent substance of between thethird separator and the fourth separator; wherein the plurality of microLED pixels are formed by etching a first surface of the emissionstructure in predetermined etch portions, and the plurality ofseparators are formed in correspondence to the etch portions.
 15. Themicro-LED display of claim 14 wherein the first, second, and third colorchanging materials include quantum dots.
 16. The micro-LED display ofclaim 14, wherein the first, second, and third color changing materialshave the same height as a height of the separator.
 17. The micro-LEDdisplay of claim 14, wherein the plurality of separators are formed onan upper surface of the first conductive semiconductor layer in adirection corresponding to the second surface of the emission structure.18. The micro-LED display of claim 14, wherein the plurality ofseparators are formed of a polymer compound or a ceramic material.